SRT engineers recently said in a press release that the MDS system improves MPG about 8% on the 5.7V8 but they felt that did not matter on the 6.1 and so left MDS off because of a valve lift problem.

On the current 5.7 Rams
the aerodynamics is so brick like
the MDS can't keep operating much above
the 60-67 mph range
particularly on blacktop pavement or windy days.

I have seen enough internet forum posts with pictures of detonation damage on 5.7 v8s, and a few crank bearing problems, that I am not convinced the 5.7 is "bullet proof"....but no engine is perfect and the Magnum 5.2/5.9 and V10 have had problems too.

"Hemi Tick" is not really an engine killer
but if you buy a truck that has had the STAR fix of the exhaust valve guides it is a plus not to have the noise.

see archived post below:
===
Chrysler has known for some time how to correct
"Hemi tick"
but so many engines and $ are involved
that they are afraid of issuing a recall or TSB.

They have a solution that your dealership can find
by checking their
"Star Online" computer data base
for solution number K59926684 or K21050787

The ticking problem is that the valve guide internal diameters are too big,
and the solution involves putting in new valves with oversize stems.

If you are still under warranty
Chrysler will pay for this,
but if you are out of warranty
it is a very expensive repair.